Homez, a homeobox leucine zipper gene specific to the vertebrate lineage

doi:10.1073/pnas.1834010100

Homez, a homeobox leucine zipper gene specific to the vertebrate lineage

^*Department of Molecular, Cellular, and Developmental Biology, Yale University, 266 Whitney Avenue, New Haven, CT 06520; ^‡Department of Genetics and Development, Columbia University, 701 West 168th Street, New York, NY 10032; ^§Department of Medicine (Hematology), 1300 Morris Park Avenue, Ullmann 925, Albert Einstein College of Medicine, Bronx, NY 10461; and ^¶Child Study Center, Yale University School of Medicine, 230 South Frontage Road, New Haven, CT 06520

Contributed by Frank H. Ruddle, June 27, 2003

Abstract

This work describes a vertebrate homeobox gene, designated Homez (homeodomain leucine zipper-encoding gene), that encodes a protein with an unusual structural organization. There are several regions within Homez, including three atypical homeodomains, two leucine zipper-like motifs, and an acidic domain. The gene is ubiquitously expressed in human and murine tissues, although the expression pattern is more restricted during mouse development. Genomic analysis revealed that human and mouse genes are located at 14q11.2 and 14C, respectively, and are composed of two exons. The zebrafish and pufferfish homologs share high similarity to mammalian sequences, particularly within the homeodomain sequences. Based on homology of homeodomains and on the similarity in overall protein structure, we deliniate Homez and members of ZHX family of zinc finger homeodomain factors as a subset within the superfamily of homeobox-containing proteins. The type and composition of homeodomains in the Homez subfamily are vertebrate-specific. Phylogenetic analysis indicates that Homez lineage was separated from related genes >400 million years ago before separation of ray- and lobe-finned fishes. We apply a duplication-degeneration-complementation model to explain how this family of genes has evolved.

Footnotes

↵ † To whom correspondence should be addressed. E-mail: bayarsaihan{at}yale.edu.
Abbreviations: BAC, bacterial artificial chromosome; En, embryonic day n; HD, homeodomain; ZHX1, zinc finger homeodomain 1.
Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accession nos. AF463423, AY258064, AY126016, AF531077, AY311507, and AY311506).